Percussive tool



April 8 1924 1,489,319

R. GOLDSCHMIDT PERCUS S IVE TOOL Filed May 8, 1923 2 SheetsSheet 1 Fig.1

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April 8 1924. U 1,489,319

R. GOLDSCHMIDT PERCUSSIVE TOOL Filed May 1923 -2 Sheets-Sheet 2 Jizuelzibr'; ZZZ 22655 ea Facial; Mam/2m L'dt.

M Jv fly JM 9" Patented Apr. 8, 1924.

UNITED STATES,

PATENT OFFICE.

RUDOLF GOLDSCHMIDT, F BEFLIN, GERMANY, ASSIGN'OR T0 DET TEKNISKE FOBGB- AKTIESELSKAB, 0F GEARIJOTTENLUND, DENMARK.

PERGUE TOOL.

Application filed my a, 1923. serial no. cause.

i To all whom it may concern:

Be it known that I, RUDOLF GomscHMm'r, a citizen of Germany, and a resident or Berlin, Germany. have invented certain new and useful Improvements in Percussive Tools (for which I have filed an application in Germany on April 25, 1922), of which the following is a specification.

This invention relates to percussive tools of the type in which a hammer rotatable on its axis is reciprocated by the centrifugal action of weights revolubly mounted on the hammer.

According to the present invention the weights are so mounted upon the hammer that they effect a turning or oscillatory movement of the hammer about its own axis. Such turning or oscillatory movement may be transmitted to the tool by the hammer direct or through the hammer casing or through the medium of a flexible diaphragm in the casing so as either to oscillate the tool in both directions or cause it to rotate step-wise.

In order that the invention may be more clearly understood, reference is hereinafter made to the accompanying drawings whereon Fig. 1 is a diagrammatic illustration of a simple form of known percussive tool.

Fig. 2 is a sectional elevation on line 22 of Figure 3 of one form of percussive tool according to the invention and Fig. 3 is a. transverse section on the line 3-3 of Fig. 2.

Fig. 4 is a side View of a modified form of percussive tool.

Fig. 5 shows a longitudinal section of the end of a further construction on line 5--5 of Figure 6 and Fig. 6 is an end view thereof.

Figs. 7 and 8 are views corresponding to Figs. 2 and 3 showing a still further modi- I fication.

Fig. 9 is a detail view hereinafter menlZlOilllGd. f 1 d l ig. 10 is a ragmentary ongitu ina section of afurther construction and Fig. 11 is transverse sectional view taken on line 11--11 of Figure 10.

their centrifugal forces R and R combine to form a resultant R which coincides with the direction of reciprocation. The hammer a can be set in progressive reciprocation by providing a stop or buffer 03 and a spring f whereby a uni-directional force is impressed upon the hammer a. The energy stored in the hammer a is dissipated by the blow upon the tool or work piece 9. The inertia of the hammer a has to be overcome by the kinetic energy of the weights 0' and 0 and it is therefore desirable to keep the inertia of the body a small and'to make the weights 0 and 0 relatively large. In applying such a device to an impact tool it is also impor tant that the hammer should be so constructed that the work stored therein is given up to the tool during impact with as little internal vibration and bending stress as possible. It is also necessary that the complete tool should be so constructed that movable and driven parts and the friction due to their movement should be eliminated as far as possible. It is the object of the present invention to construct the device accordingly.

Fig. 2 illustrates a percussive tool or mechanical hammer c is a casing enclosing the mechanism and mounted upon a sup port 9, m is a driving motor and b a flexible coupling between the motorshaft e and the driven shaft it. The shaft h is movable axially relative to the hammer a which transmits the blow to the tool 1?. through a member 9 held by a diaphragm 1*, which also serves to make the casing c oil-tight.

It is obvious that the centrifugal weights 0' and 0 (Fig. 1) cannot conveniently be arranged in the same plane, and in Fig. 2 therefore the hammer a carries two light hollow journals. is about which the centrifugal weights 0' audio rotate. The weights are integral with bevel ears 2 -4 which are driven in opposite directions by bevel gear 6. The bevel gear a" is integral with a bush h and is journalled on a stub shaft 2' and retained thereon by a collar 2'. It is splined to the shaft h. -The centrifugal forces R and B? (Fig. 3) of the weights now constitute a pair of forces which change in direction and magnitude accordin to the position of the centrifugal weig ts and tend to impart a swinging motion to the hammer.

' a about its own axis e-z This turning movement ma be transmitted to the easing and support by mounting the trunmons so as to roll orslide at Z in a groove 1' in the casing. In hand hammers this turning movement is usually transmitted to the operators hand, the vibrations thereby transmitted to the hand or support being mitigated by springs. These vibrations can be entirely overcome if, as shown in. Fig. 4, the hand grip is rotatably mounted on the hammer casing.

In percussive boring tools the turning movement can be utilized with advantage in order to turn the percussive borin too] about its axis. I In the form shown in 4 the hand grip 2 is rotatably attached at to the motor casln m and allows the whole casing together with the boring tool n to oscillate about its longitudinal axis z-z. In order to reduce the oscillating mass, the motor casing 112 may be rotata ly attached to the hammer casing c at B and the motor casing we may be fixed at A to the hand grip P. Such an arrangement is shown in Fig. 7.

The turning movement may be increased if, for example, the moment created by the centrifugal weights is not sufiicient to turn the boring tool. This may be effected by utilizing the work stored in the mass of the oscillating hammer a to produce transverse blows on the tool. The tool n may thus not only be fed forward in the direction of the axis zz but-it may be rotated about this axis by impact. The transverse blow may either be imparted to the casing by fitting the boring tool in a hexagonal or splined socket, or thecasing may oscillate and rotate with the hammer and the blow be transmitted from the casing to the tool, or the hupmer may act directly upon the boring o Fig. 5 shows an arrangement wherein the casing is assumed to swing with the hammer a. In this case the casing 0 transmits the traverse blow to the boring tool n. This construction only differs from Fig. 2 in that the shaft 8 of the boring tool is mounted rotatably in the head of the casing and carries two segmental projections t which engage two segments o projecting from the casing 0. Between the two pairs of segments are springs u. When the casing swings in the direction I, the springs are compressed (assuming that the strength of the springs is lem than the grip of the work on the boring tool). When the casing swings in the opposite direction II, the energy is dissipated in the blow upon the faces w of the segments t and is sufiicient to turn the boring tool stepwise in the direction II.

igs. 7 and 8 illustrate an arrangement wherein the boring tool is non-rotatably mounted in the casing, the transverse blow being effected inside the casing. In the casing are. two guides :v against which strike the trunnions k on the hammer a. A spring f is compressed during the backward movement of the hammer a, this spring being fastened at one end at f to one of the trunnions hand at the other end at f to a fixed collar in the casing c. It thus fulfills the double purpose of a compression spring both" for the longitudinal impact and also for the transverse impact.

Instead of transmitting the transverse impact through the medium of the casing to the boring tool, it may be transmitted direct to the tool a by the aid of the intermediate member 9 of the diaphragm r as in Figs. 10 and 11, wherein the intermediate member 9 carries projections g and 9 for guiding the hammer a and tool a respectively, the guide (7' having segmental recesses adapted to receive segments 3 on the hammer a. The diaphragm r in this arrangement must be so shaped that it not only yields in the direction z2, but may ield to torsion under the transverse blow. or this purpose it may be cup-shaped, or corrugated. The material of the diaphragm is preferably oil-proof impregnated leather. On stepwise rotation of the tool at by the transverse blow the free] rotatable casing will slowly follow up, being carried by the diaphragm. The re-action 'of the oscilla tions of the hammer a about its axis are also taken up (as in Fig. 7) by the spring f which transmits the re-action to the casing c and from thence through the flexible diaphragm r to the boring tool n which is sufficiently held by grip of the work.

If one end of the spring f is not secured at f to the hammer casing 0 but at e as in ig. 9 to the motor casing m, the casing must be allowed to rotate at the same speed as the tool in order to keep the spring constantl under tension. In this arran ement, there ore the angular velocity of the motor casing or rotatable part-thereof, for example, a rotating end cap, and consequently that of the boring tool may be regulated within certain limits.

Claims 1. A percussive tool comprising the combination of a hammer, means for supporting said hammer for longitudinal an rotary movement, centrifugal weights revolubly mounted on said hammer in such manner as tosubject said hammer both to longitudinal reciprocation and oscillation about its longitudinal axis and mechanism for revolving said weights.

2. A percussive tool comprising the combination of a hammer, a casing therefor, means for supporting said hammer in said casing for longitudinal movement therein and for rotary movement, centrifugal weights revolubly mounted in said casing and on the hammer in such manner as to subject the hammer to longitudinal reciprocation whilst oscillating said hammer about the longitudinal axis, and mechanism for revolving said weights.

3. A percussive tool as slpecified in claim 2 having means for revolub y supporting the casing. 4

4. A percussive hand tool as specified in claim 2 having a hand grip to which the hammer casing is rotatably connected.

5. A percussive tool as specified in claim 1 in which both the longitudinal and oscillatory movement of the hammer is transmitted to a rotary tool.

6. A percussive tool as specified in claim 1 having means whereby the oscillatory movement of the hammer effects stepwise rotation of a rotary tool.

7. A percussive tool as specified'in claim 1 having a casing enclosing the hammer and weights, a tool supported by said casing and means interposed between said tool and hammer whereby the hammer imparts a forward blow to the tool and oscillation thereof.

8. A percussive tool as specified in claim 2 having a tool supported by the casing and means whereby said casing efiects stepwise rotation of said tool.

9. A percussive tool as specified in claim 1 having a spring against which the ham- 80 mer reacts during its oscillation.

10. A percussive tool as specified in claim against which the ham- 1 having a sprin during its oscillation and mer reacts both reciprocation.

11. A percussive tool as specified in claim 2 having a coil spring connected at one end to the hammer and at the other end to the casing.

12. A percussive tool as specified in claim 2 in which the casing is revoluble and in which a spring is connected at one end to the hammer and at the other end to the casing. 13. A percussive tool comprising the combination of a hammer, a casing enclosing the hammer, means for supporting said casing for longitudinal movement therein and for rotary movement, abutments for limiting oscillation of said hammerin said casing, centrifugal weights revolubly mounted in said casing and on the hammer for subjecting said hammer to reciprocation and oscillation, means for revolubly supportin said casing, a tool supported to turn wit said casing and a member fluid-tight in saidcasing between said tool and hammer.

14. A percussive tool as specified in claim 13 having a spring between the hammer and casing and connected thereto.

In testimony whereof I hereunto aflix my signature.

RUDOLF GOLDSCHMIDT. 

